COMPLIANCE INFO_JTD 9/3/2025 - Laserfiche WebLink

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Foothill Sanitary Landfill Page 19 of 53 San Joaquin County DPW - Solid Waste Joint Technical Document Revised 6/09/2020 not analyzed for stability under dynamic conditions due to their temporary nature. The updated stability report concludes that the global dynamic stability for the final landfill configuration, which has 3 to 1 slopes and 15 foot wide benches every 50 feet, meets the requirements set forth in Title 27 CCR. The landfill’s slopes can be seen on the final grading plan presented in Figure 6. Because the calculated factor of safety under dynamic conditions (seismic loading) is greater than 1.5, we have concluded that there should not be any movement of the refuse mass during an MPE event. 5.3.5. Maximum Height The maximum height of the refuse fill is 432 feet MSL. The County may seek to raise the permitted height limit, subject to regulatory approval. A height increase will require revision of the Preliminary Closure/Post Closure Maintenance Plan. 5.3.6. Minimum Refuse Elevation The lowest elevation of refuse at the landfill is anticipated to be 180 feet MSL (Table 2), approximately three feet above the base of excavation (Figure 5). 5.3.7. Minimum Five-Foot Separation to Groundwater The minimum separation between groundwater and refuse is approximately 140 ft, which exceeds the minimum regulatory requirement of five feet (Table 3). This estimate includes the effect of capillary rise, which is dependent upon the pore size of the soil. Gravel and sand/sandstone are the predominant soil types at that elevation (Appendix E). The sandstone is described as weakly or moderately cemented so the pore size would be smaller than that of clean sand, but likely not as small as the pore size of clay. Based on the information given, the maximum capillary rise at the site is estimated to be 3.25 feet. 5.3.8. Service Area